How to fly a drone through Crossrail's tunnels

10 March 2015 Last updated at 15:07 GMT

For the first time, the BBC has been allowed to fly a remote controlled camera along the tunnels of Crossrail, the giant building project that will eventually see trains criss-crossing London and the South East on a brand new train line.

It took four months of negotiating with the Crossrail safety team, but eventually they agreed that a BBC trained pilot, Jon Bontoft, could go down with our transport team, Richard Westcott and Jonathan Sumberg.